Cellulase enzymes have been used in detergent compositions for many years now for their known benefits of depilling, softness and colour care. However, the use of most of cellulases has been limited because of the negative impact that cellulase may have on the tensile strength of the fabrics' fibers by hydrolysing crystalline cellulose. Recently, cellulases with a high specificity towards amorphous cellulose have been developed to exploit the cleaning potential of cellulases while avoiding the negative tensile strength loss. Especially alkaline endo-glucanases have been developed to suit better the use in alkaline detergent conditions.
For example, Novozymes in WO02/099091 discloses a novel enzyme exhibiting endo-beta-glucanase activity (EC 3.2.1.4) endogenous to the strain Bacillus sp., DSM 12648; for use in detergent and textile applications. Novozymes further describes in WO04/053039 detergent compositions comprising an anti-redeposition endo-glucanase and its combination with certain cellulases having increased stability towards anionic surfactant and/or further specific enzymes. Kao's EP 265 832 describes novel alkaline cellulase K, CMCase I and CMCase II obtained by isolation from a culture product of Bacillus sp KSM-635. Kao further describes in EP 1 350 843, alkaline cellulase which acts favourably in an alkaline environment and can be mass produced readily because of having high secretion capacity or having enhanced specific activity.
We have found that the combination of alkaline bacterial endoglucanases and hueing agents deliver improved, synergistic whitening benefits. Without wishing to be bound by theory, it is believed that the following mechanisms are likely to give rise to such benefits: the endoglucanase enzyme hydrolyses amorphous cellulose present on the cotton surface, and thereby assists the removal of yellow soils and opens up the pore structure of the fabric making it more accessible to dye molecules. The resulting combination of improved yellow soil removal and improved shading colorant deposition leads to an improvement in fabric appearance. These combined effects hence contribute to a surprising improvement in visual perception and hence, in cleaning perception.